Use of ppar activators for the treatment of pulmonary fibrosis

ABSTRACT

An activator of PPAR gamma is useful for the treatment of pulmonary fibrosis.

FIELD OF THE INVENTION

This invention relates to a new use for known compounds; and inparticular to the therapeutic use of PPAR activators.

BACKGROUND OF THE INVENTION

Interstitial lung disease (ILD) is a broad category of lung diseasesthat includes more than 130 disorders which are characterized byscarring of the lungs. ILD accounts for 15% of the cases seen bypulmonologists (lung specialists). Another name for ILD is pulmonaryfibrosis. Some of the interstitial lung disorders include: idiopathicpulmonary fibrosis, hypersensitivity pneumonitis, sarcoidosis,eosinophilic granuloma, Wegener's granulomatosis, idiopathic pulmonaryhemosiderosis and bronchiolitis obliterans.

Approximately two-thirds of these conditions have no known cause and aretherefore termed idiopathic pulmonary fibrosis (IPF). Known causesinclude: occupational and environmental exposure, inorganic dust(silica, hard metal), organic dust (bacteria, animal proteins), gases,fumes, drugs and poisons, chemotherapy, antibiotics (this is rare),radiation therapy, infections (including residues of active infection ofany type), connective tissue disease, systemic lupus erythematosus,rheumatoid arthritis and progressive systemic sclerosis.

The most common symptoms of ILD are shortness of breath with exerciseand a non-productive cough. Some people also exhibit fever, weight loss,fatigue, muscle and joint pain, and abnormal chest sounds, dependingupon the cause.

ILD is a disease in which tissue in the lungs called the interstitiumbecomes inflamed or scarred. The interstitium includes a portion of theconnective tissue of the blood vessels and alveoli (air sacs) and makesup the membrane where the exchange of oxygen and carbon dioxide takesplace. After the inflammation occurs, scarring, or fibrosis, develops.The general pattern is: injury to lung cells, inflammation, andfibrosis. The progression of ILD can vary from person to person, andeach person responds differently to treatment. Many doctors characteriseILD in stages, to indicate how much of the affected lung tissue isinflamed and how much is scarred.

The PPARγ receptor is a subtype of the PPAR (peroxisomeproliferator-activated receptor) family of nuclear hormone receptors. Ithas been shown to function as an important regulator in lipid andglucose metabolism, adipocyte differentiation, inflammatory response andenergy homeostasis.

The thiazolidinediones rosiglitazone and pioglitazone are used for thetreatment of insulin resistance in type 11 diabetes. Thiazolinedioneactivators of PPARγ have also been shown to have anti-proliferative andanti-inflammatory effects in vascular myocytes and macrophages.Furthermore, troglitazone has been shown to have anti-proliferativeeffects on keratinocytes in psoriasis. In this disease, keratinocytehyperproliferation and immune dysfunction are major components. Suchcompounds and their utility in therapy are described in U.S. Pat. No.5,594,015, U.S. Pat. No. 5,824,694, U.S. Pat. No. 5,925,657 and U.S.Pat. No. 5,981,586.

Conversely, activators of the alpha subtype of the PPAR (PPARα), whichinclude such compounds as clofibrate and gemfibrozil, have beendescribed in U.S. Pat. No. 6,060,515 for their ability to enhanceepithelial barrier development. Acting through an effect ontrans-epithelial water loss, hypertrophic scars and keloids are amongmany skin conditions that are said to be susceptible to such treatment.

Inflammatory leukocytes, for example eosinophils, neutrophils ormacrophages, are thought to play a role in the inflammatory component ofrespiratory diseases.

The use of PPARγ agonists for the treatment of a disease or conditionassociated with increased numbers of neutrophils and/or neutrophilover-activation is described in WO00/62766.

The use of anti-inflammatory or immunosuppressive agents in thetreatment of ILD, asthma or chronic obstructive pulmonary disease (COPD)is well known. These drugs have effects on inflammatory leukocytes, forexample reducing their number and/or deactivating them (Baughman et al.,Curr. Opinion Pulm. Med. 2001 September; 7(5): 309-313). Such agentsinclude corticosteroids, which are a common option and regarded as thegold standard of anti-inflammatory agents. Despite their effectivenessin controlling inflammation, they do not address other elements of thesediseases, including fibrosis.

ILD, asthma and COPD include a range of responses to anti-inflammatoryagents such as corticosteroids. Recent data indicate that, followingsuch treatment, less than 30% of IPF patients show objective evidence ofimprovement (Allen et al, Respir. Res. 2002; 3: 13). Most asthmaticpatients respond well to corticosteroids but some are known to be poorlyresponsive, and it has been suggested that, in such patients,fibrogenesis dominates over inflammation (Bosse et al., Am. J. Respir.Crit. Care Med. 1999 February; 159(2): 596-602). Inhaled corticosteroidsare widely prescribed for the treatment of stable COPD, despite lack ofproven efficacy, indicating that steroids do not appear to redress thenon-inflammatory pathophysiology that is thought to be important in thepathogenesis of this disease (Culpitt et al, Am. J. Respir. Crit. CareMed. 1999 November; 160(5 Pt 1):1635-9).

Recent evidence suggests that lung myofibroblasts play an important rolein the progression of pulmonary fibrosis (Uhal et al. 1998, Am. J.Physiol. 275 (Lung Cell. Mol. Physiol. 19): 1192-1199). In particular,these myofibroblasts are capable of inducing death in alveolarepithelial cells and it is believed that accumulating fibroblasts inhuman lung tissue are found in close proximity to unrepaired or abnormalalveolar epithelium (Uhal et al., supra). Alveolar cells have importantantifibrotic functions (Simon et al. 1995, in Pulmonary Fibrosis, ed.Phan & Thrall, New York Dekker vol. 80, pp 511-540) and it may beconcluded that myofibroblast actions cause, directly and or indirectly,fibrosis of the lung.

SUMMARY OF THE INVENTION

Surprisingly, it has been found that an activator of PPAR gamma such aspioglitazone has the ability to reduce numbers of viable lungmyofibroblasts and thereby, as explained above, reduce the lungfibrosis. According to the present invention, a PPARγ agonist may beused to treat any form of ILD, including those to which reference ismade above. The invention is particularly useful where the condition hasa fibrotic component.

The ILD or pulmonary fibrosis that is treated may be a component ofanother condition, e.g. chronic obstructive pulmonary disease (COPD) orasthma. It may also be the third stage of acute respiratory diseasesyndrome (ARDS), i.e. following the usual first and second stages ofpathology, i.e. damage to epithelial cells, and proliferation.

The invention may involve treatment or prevention of conditions. As anexample of the latter, one type of pulmonary fibrosis is associated withdrug treatments including bleomycin, amiodarone as well as radiotherapy(in a percentage of patients). This may be treated prophylactically witha PPAR agonist, to prevent the occurrence of fibrosis.

It is now evident that the use of PPARγ agonists for treatment of afibrotic state, condition or disease of the lung in a host sufferingtherefrom has not been described before. Neither has the use of PPARγagonists for treatment of ILD, asthma or COPD in a host wherein theinflammation is adequately treated, e.g. by corticosteroids.

Accordingly, the present invention particularly provides:

-   -   the use of a PPARγ agonist for the treatment of ILD, asthma or        COPD in a host in need thereof, wherein the host is not in need        of anti-inflammatory treatment;    -   the use of a PPARγ agonist for the treatment of ILD, asthma or        COPD in a host in need thereof, wherein the host is not in need        of treatment to address the adverse effects of increased numbers        of neutrophils and/or neutrophil overactivation in the lung;    -   the use of a PPARγ agonist for the treatment of ILD, asthma or        COPD in a host in need thereof, wherein the host is concurrently        treated with an effective dose of a corticosteroid or other        anti-inflammatory agent; and    -   the use of a PPARγ agonist for the treatment of ILD, asthma or        COPD in a host in need thereof, wherein the host is concurrently        treated with an effective dose of a corticosteroid or other        agent to redress the increased numbers of neutrophils and/or        neutrophil overactivation in the lung.

DESCRIPTION OF PREFERRED EMBODIMENTS

Any PPARγ activator may be used in this invention provided it has thedesired activity. Well known activators of this receptor include thethiazolidinediones, troglitazone, pioglitazone, rosiglitazone andciglitazone, isaglitazone, darglitazone and englitazone. It will beunderstood that a prodrug or metabolite for such a compound can be used.Other non-thiazolidinedione compounds have recently been identified suchas the phenyl alkanoic acids described in WO97/31907 and WO00/08002, theoxazoles and thiazoles described in WO99/58510, the oximinoalkanoicacids described in WO01/38325, the benzoic acid derivatives described inWO01/12612, the sulphonamides described in WO99/38845, theβ-aryl-α-oxysubstituted alkylcarboxylic acids described in WO00/50414,and the quinolines described in WO00/64876 and WO00/64888. In addition,the natural compound 15-deoxy-γ-12,14-prostaglandin J2 has also beenfound to be a ligand for PPARγ and to have effects mediated through thisreceptor (Forman et al, Cell 93(5): 813-819, 1995). Similar effects havealso been found for metabolites of 15-deoxy-Δ-12,14-prostaglandin J2(Kliewer et al, Cell 83(5): 813819, 1995) and for various fatty acidsand eicosanoids (Kliewer et al, PNAS USA 94(a): 4318-4323, 1997).

Despite the structural variation tolerated by PPARγ, there is asubstantial similarity in biological effect due to activation of thisreceptor. PPAR agonists share a common binding mode to their receptors.Despite differences in the chemical structure of these agonists, theacidic headgroups of these agonist ligands accept a hydrogen bond from atyrosine residue in the AF2 helix and/or a histidine or tyrosine residuein helix-5 (see description in WO01/17994). Compounds with the abilityto activate PPARγ receptors can be expected to be useful in thisinvention.

For use in the invention, therapeutic compounds may be administered tohuman patients topically or by subcutaneous injection. Oral andparenteral administration are used in appropriate circumstances apparentto the practitioner. Preferably, the compositions are administered inunit dosage forms suitable for single administration of precise dosageamounts. Guidance on formulations of this type is provided inWO02/087576 (the content of which, and of all other publicationsidentified herein, is incorporated by reference).

The active agent is preferably administered by inhalation, e.g. to thelower lung. This may be achieved through control of particle properties(including shape, size and electrostatic forces), using a dry powder orliquid particle formulation. Suitable particle sizes are up to 1 μm, orup to 5 μm or above, depending on the intended target.

The dosage of active agent for pulmonary administration can bedetermined by one skilled in the art, based on factors such as thecondition of the patient, the severity of the disease and frequency ofadministration. It is typically 0.01 mg to 1000 mg.

The concentration of PPARγ activator required to have a maximallyeffective antifibrotic effect in the lungs may be higher than that whichmay be safely achieved clinically by administration of the activator viaany route other than the inhaled route. For example, maintained freeplasma concentrations of pioglitazone following oral administration toman, of conventional clinical dosages, would be expected to besubstantially below 10 μM.

The active agent may be provided in a device suitable for pulmonarydelivery, for delivery topically to the lung. This can be achieved usinga range of pulmonary systems and formulation techniques known to thoseskilled in the art such as, but not limited to, nebulisers, multi-doseinhalers, dry powder inhalers and pressurised metered multi-doseinhalers. The active agent can be readily formulated for inhalation,e.g. with one or more conventional additives such as carriers,excipients, surface active agents etc.

In addition to the therapeutic compound, the compositions may include,depending on the formulation desired, pharmaceutically acceptable,non-toxic carriers or diluents, which include vehicles commonly used toform pharmaceutical compositions for animal or human administration. Thediluent is selected so as not to unduly affect the biological activityof the combination. In addition, the pharmaceutical composition orformulation may include additives such as other carriers, adjuvants ornon-toxic, non-therapeutic, non-immunogenic stabilizers and the like.

Furthermore, excipients can be included in the formulation. Examplesinclude cosolvents, surfactants, oils, humectants, emollients,preservatives, stabilizers and antioxidants. Any pharmacologicallyacceptable buffer may be used, e.g., Tris or phosphate buffers.Effective amounts of diluents, additives and excipients are those whichare effective to obtain a pharmaceutically acceptable formulation interms of solubility, biological activity, etc.

The term “unit dosage form” refers to physically discrete units suitableas unitary dosages for human subjects and animals, each unit containinga predetermined quantity of active material calculated to produce thedesired pharmaceutical effect in association with the requiredpharmaceutical diluent, carrier or vehicle. The specifications for theunit dosage forms of this invention are dictated by and dependent on (a)the unique characteristics of the active material and the particulareffect to be achieved, and (b) the limitations inherent in the art ofcompounding such an active material for use in humans and animals.

Examples of unit dosage forms are tablets, capsules, pills, powderpackets, wafers, suppositories, granules, cachets, teaspoonsful,tablespoonsful, droppersful, ampoules, vials, aerosols with metereddischarges, segregated multiples of any of the foregoing, and otherforms as herein described.

Thus, a composition for use in the invention includes a therapeuticcompound which may be formulated with one or more conventional,pharmaceutically acceptable vehicles, preferably for pulmonaryadministration. Formulations may also include small amounts of adjuvantssuch as buffers and preservatives to maintain isotonicity, physiologicaland pH stability. Means of preparation, formulation and administrationare known to those of skill. See generally Remington's PharmaceuticalScience 15th ed., Mack Publishing Co., Easton, Pa. (1980).

Slow or extended-release delivery systems, including any of a number ofbiopolymers (biological-based systems), systems employing liposomes, andpolymeric delivery systems, can be utilized with the compositionsdescribed herein to provide a continuous or long-term source oftherapeutic compound. Such slow release systems are applicable toformulations for topical, ophthalmic, oral, and parenteral use.

Further information of relevance may be found in WO02/087576, includingevidence of the utility of PPARγ activators to affect fibroblasts.Evidence on which this invention is more particularly based is in thefollowing Example.

EXAMPLE

Primary human lung fibroblasts were derived from patients with ILD(Idiopathic Pulmonary Fibrosis or Chronic Hypersensitivity Pneumonitis).Patients had clinical, functional and radiologic features which fulfilthe diagnostic criteria for an ILD. Briefly, they had progressivedyspnea, bilateral reticulonodular images on chest roentgenogram,restrictive lung functional impairment, with decreased lung volumes andcompliance, and hypoxemia at rest that worsened with exercise.

The methods used to isolate and culture the lung fibroblasts and countcells are described in Wang et al, Am. J. Physiol. Lung 277:L1158-1164(1999). In brief, lung fibroblasts were isolated by trypsin digestion oftissues minced to 1 mm² fragments. Fibroblast/myofibroblast strains wereestablished in Dulbecco's modified Eagle's medium (or in Hams F-12medium) supplemented with 10% fetal calf serum, 200 U/ml penicillin, and200 mg/ml streptomycin, and were cultured in 24-well plates. All cellswere cultured at 37° C. in 95% air-5% carbon dioxide. For theseexperiments, 2 strains were used.

In order to quantify myofibroblast numbers, the myofibroblast markeralpha-smooth muscle actin (α-SMA) was measured. Detection of α-SMA wasachieved with a fluorescent (FITC) monoclonal antibody specific forα-SMA applied to ethanol-fixed cells (see Wang et al., referencedabove).

In a first experiment, the 2 strains were grown to 70-80% confluence.The cells were exposed to pioglitazone at 3 μM or drug vehicle for 3days, after which the number of α-SMA positive cells was quantified(sample size 24) as a percentage of total cells. For one strain, thepercentage of α-SMA cells was 27 (standard error mean 3.7) with controland 17 (standard error mean 2.5) in the presence of 3 μM pioglitazone.The drug effect was statistically significant (P≦0.01Student-Newman-Keuls Multiple Comparisons Test). For the second strain,the respective values were 30.6 (standard error of mean 2.7) and 26(standard error of mean 2.9) although the difference was notstatistically significant.

In a second experiment, the effect of pioglitazone on the second strainwas studied again, but the exposure time was increased to 10 days andthe effects of lower and higher concentrations (1 μM and 10 μM) werestudied. After 10 days treatment with vehicle, the percentage of α-SMAcells was 16.5 (standard error of mean 2.7); after 10 days treatmentwith pioglitazone at 1 μM the percentage was 15.3 (standard error ofmean 1.8); and after treatment with pioglitazone at 10 μM the percentageof α-SMA cells was 7.4 (standard error of mean 1.8) (all n=4). Thereduction in α-SMA cells by 10 μM pioglitazone was significant (P≦0.05Dunnett Multiple Comparisons Test). In this experiment, there were nosignificant changes in total cell numbers.

These data clearly establish the ability of pioglitazone to reducenumbers of human lung myofibroblasts.

1. A method for treating pulmonary fibrosis wherein said methodcomprises administering, to a patient in need of such treatment, anactivator of PPARy.
 2. The method, according to claim 1, wherein theactivator is a thiazolinedione.
 3. The method, according to claim 1,wherein the activator is pioglitazone.
 4. The method, according to claim1, wherein the activator of PPARy is administered by inhalation.
 5. Themethod, according to claim 1, wherein the pulmonary fibrosis isassociated with COPD.
 6. The method, according to claim 1, wherein thepulmonary fibrosis is associated with asthma.
 7. The method, accordingto claim 1, wherein the pulmonary fibrosis is associated with acuterespiratory distress syndrome (ARDS).
 8. The method, according to claim7, wherein the pulmonary fibrosis is associated with the third stage ofARDS.
 9. The method, according to claim 1, used for the treatment ofpulmonary fibrosis in a patient who is undergoing chemotherapy.
 10. Themethod, according to claim 1, used for the treatment of pulmonaryfibrosis in a patient who is undergoing radiation therapy.
 11. Themethod, according to claim 1, used for the treatment of pulmonaryfibrosis in a patient who is undergoing therapy with amiodarone.
 12. Themethod, according to claim 1, used for the treatment of idiopathicpulmonary fibrosis.
 13. The method, according to claim 1, used for thetreatment of pulmonary fibrosis in a patient who is undergoing therapywith an anti-inflammatory agent.
 14. The method, according to claim 13,wherein the anti-inflammatory agent is corticosteroid.
 15. The methodaccording claim 1, used for the treatment of pulmonary fibrosis in apatient who is resistant to treatment with corticosteroids.
 16. Aformulation for inhalation, comprising an activator of PPARy.
 17. Adevice for pulmonary delivery, comprising activator of PPARy.
 18. Theformulation, according to claim 16, wherein the activator is athiazolinedione.
 19. The formulation, according to claim 16, wherein theactivator is pioglitazone.
 20. The device, according to claim 17,wherein the activator is a thiazolinedione.
 21. The device, according toclaim 17, wherein the activator is pioglitazone.